1. Field of the Invention
The present invention relates to an image forming apparatus such as a laser printer, and more particularly to an image forming apparatus having a duplex printing unit, which is detachably mounted on a main body. The present application is based on Korean Patent Application No. 2001-8242, which is incorporated herein by reference.
2. Description of the Related Art
Generally, a laser printer is representative of image forming apparatuses that use a photo electric printing method for transferring and settling an image on a printing paper after developing an electrostatic latent image formed by scanning a laser beam on a charged photosensitive medium into a visible image by a toner, and the laser printer prints out requested information related to a computer network in page units.
These image forming apparatuses such as a laser printer and a photocopying machine comprise a duplex printing unit for circulating a printing paper to an image forming engine to print out each requested information on both sides of a printing paper, respectively.
In a conventional image forming apparatus, since a duplex printing unit is integrally built in a main body of a printer, it is difficult to make a compact-type printer. Some of the problems associated with the conventional image forming apparatus, which is constructed such that a printing paper circulation path is closed inside of a main body, include dealing with jammed papers and repair.
The present invention has been made to overcome the above-mentioned problems of the related art. Accordingly, it is an object of the present invention to provide an image forming apparatus capable of duplex printing. The image forming apparatus is modularly constructed such that a duplex printing unit is selectively removable as needed and has a more compact construction.
Another object of the present invention is to provide an image forming apparatus capable of duplex printing having a function that enables a user to deal with a jammed paper generated in a circulation path during printing.
The above objects are accomplished by an image forming apparatus that includes a main body having an engine unit for forming image information on a printing paper and a printing paper transferring path formed therein, along which a printing paper on a cassette is transferred via the engine unit, and a duplex printing unit having a printing paper circulation path formed therein, which is constructed so that a printing paper can re-enter after being reversed in the printing paper transferring path. The duplex printing unit is adapted to be selectively removed from and mounted on the main body.
It is preferable that the duplex printing unit includes: a door panel and a cover panel which are connected to be capable of relative turning by facing each other for forming the printing paper circulation path; printing paper transferring means that is provided on a facing side of the door panel and the cover panel; a power transmission means for transmitting power generated from a driving unit of the main body to the printing paper transferring roller, when mounting the door panel and the cover panel to the main body; and a complementary connection means for connecting the door panel and the cover panel with the main body complementarily.
It is preferable that the printing paper transferring means includes a plurality of transferring rollers and back-up rollers that are installed corresponding to each facing side of the door panel and the cover panel and are engaged with each other.
It is also preferable that the power transmission means is constructed including a driving gear that is installed on a rotational axis of the transferring roller to be engaged with a swing gear formed to be connected with the driving unit of the main body.
In addition, it is advisable that the complementary connection means has four pairs of supplementary members: a pair of flexible ribs protruding from one end of either the door panel or the cover panel; a pair of hinge shafts formed at the end of the elastic ribs; a pair of guide grooves formed on both side walls of a removable unit of the main body for the hinge shafts to slide therealong; and a pair of hinge holes formed at each end of the guide grooves for receiving the hinge shafts.